Tire inflation systems are configured to maintain a desired level of air pressure within vehicle tires during operation of the vehicle. The system must transfer air from a non-rotating component through a rotating wheel component such as the wheel hub, for example. Most air passages internal to wheel hubs are created using intersecting “rifle-drilled” holes. A typical rifle-drilled hole arrangement includes at least two holes that intersect each other. In one configuration, a first rifle-drilled hole is made to extend in a generally axial direction along a length of the wheel hub. A second rifle-drilled hole is drilled from an outer peripheral surface of the wheel hub in an inward direction to intersect the first rifle-drilled hole.
Due to the nature of drilling long holes, it is sometimes difficult to ensure that the drilled holes properly intersect. If the holes fail to intersect properly, the result is an improperly formed air passage. Further, as the second rifle-drilled hole extends through the outer peripheral surface, it can be difficult to provide an air-tight passage.